Structure Design And Research On Ice-coring Drill With Air Reverse Circulation For Ice Layer

The polar region is a mysterious place.Both the South Pole and the North Pole are repositories of knowledge needed for scientific exploration.Ice core is the key to the treasure,which is of great research value to glaciology,climatology and biology.In order to obtain the ice core,scientists of various countries have conducted a large number of scientific drilling,and have developed many ice coring drills.In this paper,ice coring drill is investigated and analyzed.Combined with the characteristics of reverse circulation drilling technology,a new type drilling tool with high efficiency,fast drilling speed and convenient operation--air reverse circulation ice coring drill is studied.The drill is designed to drill 200 m.The development and application of the drill can lay a foundation for the study of the Antarctic regional geological structure,deep ice core drilling and scientific exploration hole drilling.The technology can be drilled in Antarctic glaciers or the glacial tundra.In this paper,the design parameters of reverse-circulation drilling tool are determined by reverse-circulation calculation and numerical simulation for improving the drilling efficiency.The air reverse-circulation test was designed and studied,and the technological parameters of air reverse-circulation were obtained.Verify the reliability of ice reverse-circulation drill.It provides an important reference for further design and optimization of the structure parameters of the air reverse circulation ice coring drill,on improving the drilling efficiency and obtaining a better ice core.The main conclusions of this paper are as follows:(1)Put forward the design of air reverse circulation ice coring drill,carried out theoretical calculation on the reverse circulation transportation system,and determined the influencing factors of the reverse circulation efficiency.The key technology of drilling tool is the formation of reverse circulation,whether the gas can carry ice core and ice chips.Through the method of hydrodynamics,the minimum flow and velocity are calculated for the air reverse circulation transportation and pressure loss.(2)The mechanical calculation of ice core fracture was carried out,and the numerical simulation analysis of the process of ice core fracture was solved through ABAQUS software to obtain the data of ice core fracture.Combined with the design of drilling tool,the size of the core breaker and the size of the center channel are obtained.(3)Reverse circulation of ice core and ice chips experiment was did to obtain the experimental data and make a comparison,so as to obtain the influence of the inner diameter of the center channel on the speed.Combined with the design of the structure,the migration speed of ice core and ice debris in the center channel with an inner diameter of 69 mm was determined under the operation of a large flow air compressor.Compared with the calculation results,it is found that there is a certain error between the calculation and the experiment,but it also has some reference significance.(4)CFD software FLUENT was used to calculate the air flow field characteristics of the reverse-circulation drill.The relationship between velocity and pressure in drilling tool is studied.The proper structure of reverse circulation drill pipe is obtained.